/* @(#)pmap_prot2.c 2.1 88/07/29 4.0 RPCSRC */
/*
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*/
#if !defined(lint) && defined(SCCSIDS)
static char sccsid[] = "@(#)pmap_prot2.c 1.3 87/08/11 Copyr 1984 Sun Micro";
#endif
/*
* pmap_prot2.c
* Protocol for the local binder service, or pmap.
*
* Copyright (C) 1984, Sun Microsystems, Inc.
*/
#include
#include
#include
/*
* What is going on with linked lists? (!)
* First recall the link list declaration from pmap_prot.h:
*
* struct pmaplist {
* struct pmap pml_map;
* struct pmaplist *pml_map;
* };
*
* Compare that declaration with a corresponding xdr declaration that
* is (a) pointer-less, and (b) recursive:
*
* typedef union switch (bool_t) {
*
* case TRUE: struct {
* struct pmap;
* pmaplist_t foo;
* };
*
* case FALSE: struct {};
* } pmaplist_t;
*
* Notice that the xdr declaration has no nxt pointer while
* the C declaration has no bool_t variable. The bool_t can be
* interpreted as ``more data follows me''; if FALSE then nothing
* follows this bool_t; if TRUE then the bool_t is followed by
* an actual struct pmap, and then (recursively) by the
* xdr union, pamplist_t.
*
* This could be implemented via the xdr_union primitive, though this
* would cause a one recursive call per element in the list. Rather than do
* that we can ``unwind'' the recursion
* into a while loop and do the union arms in-place.
*
* The head of the list is what the C programmer wishes to past around
* the net, yet is the data that the pointer points to which is interesting;
* this sounds like a job for xdr_reference!
*/
bool_t
xdr_pmaplist (xdrs, rp)
XDR *xdrs;
struct pmaplist **rp;
{
/*
* more_elements is pre-computed in case the direction is
* XDR_ENCODE or XDR_FREE. more_elements is overwritten by
* xdr_bool when the direction is XDR_DECODE.
*/
bool_t more_elements;
int freeing = (xdrs->x_op == XDR_FREE);
struct pmaplist *next = NULL;
while (TRUE)
{
more_elements = (bool_t) (*rp != NULL);
if (!INTUSE(xdr_bool) (xdrs, &more_elements))
return FALSE;
if (!more_elements)
return TRUE; /* we are done */
/*
* the unfortunate side effect of non-recursion is that in
* the case of freeing we must remember the next object
* before we free the current object ...
*/
if (freeing)
next = (*rp)->pml_next;
if (!INTUSE(xdr_reference) (xdrs, (caddr_t *) rp,
(u_int) sizeof (struct pmaplist),
(xdrproc_t) INTUSE(xdr_pmap)))
return FALSE;
rp = freeing ? &next : &((*rp)->pml_next);
}
}
INTDEF(xdr_pmaplist)